linux-kernel - Re: [PATCH] dma: ste_dma40: Remove VLA usage

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Message-ID: <CAK8P3a30Q1ezvCWfudUY=z1q3NHdrkbwRsmSDso4s7TifQAmNQ@mail.gmail.com>
Date:   Fri, 29 Jun 2018 23:22:22 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Kees Cook <keescook@...omium.org>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        dmaengine@...r.kernel.org, Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vkoul@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] dma: ste_dma40: Remove VLA usage

On Fri, Jun 29, 2018 at 8:51 PM, Kees Cook <keescook@...omium.org> wrote:
> In the quest to remove all stack VLA usage from the kernel[1], this
> switches to using a pre-allocated scratch register space, set up with
> all other other allocations.
>
> [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com
>
> Cc: Linus Walleij <linus.walleij@...aro.org>
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Vinod Koul <vkoul@...nel.org>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: dmaengine@...r.kernel.org
> Signed-off-by: Kees Cook <keescook@...omium.org>

I looked too long at this one, in short:

- Your change looks correct to me
- It could be done better in many ways, all of which would
  involve cleaning up some of the existing code in the process
- Nobody uses this driver in practice, as the hardware platform
  was a dead end

Reviewed-by: Arnd Bergmann <arnd@...db.de>